Eyewitness testimony was shaky, so Cook County prosecutors relied on a fingerprint lifted from a laptop as their key evidence in the trial of a juvenile charged with robbery. The strategy did not go well.

Presiding over the 2016 case, Judge Stuart Katz ripped into the competence of Chicago police Sgt. Thurston Daniels III, the forensics expert who testified that he had matched the print to the defendant.

“He seems oblivious and doesn’t seem concerned about educating himself as to what’s going on in his own field,” Katz said before finding the youth not guilty. He added that Daniels’ shortcomings were a symptom of a much bigger problem with Chicago police and fingerprints.

“The Chicago Police Department procedures, where they have no audits, no verification of their procedures, no participation — they don’t follow the FBI rules — casts a doubt on their whole departmental procedures,” the judge said.

Chicago police have taken a reputational battering in recent years as they struggle with high numbers of murders and shootings, low rates for solving violent crimes and fallout from questionable use of deadly force.

Getting far less attention is concern among experts about how police in the city process fingerprint evidence of non-violent misdeeds, including burglary, theft and other property crimes that collectively last year accounted for three of every four crimes reported in Chicago.

Although they handle fingerprints collected at crime scenes across the city, the Chicago Police Department’s fingerprint unit has severe deficiencies, according to an expert review commissioned by the Cook County Public Defender’s office and included in pre-trial motions the office says it routinely files in cases that turn on fingerprint evidence. The unit has no quality control and keeps poor documentation; examiners have minimal training and often testify in court using language discouraged by professional associations. The unit has not obtained accreditation from an outside group of experts, which the Department of Justice recommends as a signal that its procedures and documentation meet industry standards.

The public defender’s office says that since 2016 it has called attention to those problems to successfully poke holes in testimony by the unit’s examiners, which has led to not-guilty verdicts in four property crime cases and favorable plea deals in nearly a dozen more.

The public defender’s office told the Better Government Association that, going forward, it can likely use the noted deficiencies to undermine prosecutions in any property crime cases that turn primarily on fingerprint evidence — potentially leaving the crimes unsolved and unpunished.

Chicago’s latent print lab has fallen far behind industry best practices, which have undergone significant revisions in the past decade. Some of those reforms followed a 2009 report from the National Academy of Sciences that raised questions about the scientific foundation of all pattern evidence, including fingerprints.

Pattern evidence, the markings or impressions left at crime scenes, has long been a staple of criminal forensics. It ranges from fingerprints and shoe prints to tire treads and handwriting. Experts say such evidence can be useful in the legal system but should not be considered infallible or treated as objective science — particularly if proper quality control measures are not taken.

“When fingerprint analysis is done correctly, it’s valuable and powerful evidence,” said Glenn Langenburg, one of the fingerprint experts who reviewed the Chicago unit’s procedures. “The concern is we have no way of knowing how good the CPD is at what they’re doing. They’re not following standards.”

Bad science in the Chicago Police Department

There’s an irony to the weaknesses now plaguing Chicago’s fingerprint processing unit: Using fingerprints to help solve crimes was essentially born in the city following the 1910 murder of railroad clerk Clarence Hiller, who was shot during a burglary at his Southwest Side home in what is now the Beverly neighborhood. A jury found Thomas Jennings guilty of the crime based largely on prints lifted from a freshly painted porch railing.

The conviction was upheld the following year by the Illinois Supreme Court, which found fingerprint evidence admissible. It was the first such ruling by an appellate court in the United States.

An excerpt from the Chicago Tribune, Nov 11, 1910, describing the first criminal trial to use fingerprints as evidence.

Over the ensuing decades, Chicago police built a reputation for state-of-the-art forensics, and by the 1950s and 1960s the department became known for what was then a cutting-edge approach to analyzing crime-scene evidence.

But a resource crunch left the department struggling to keep up with advances in forensic technology and the police crime lab became overwhelmed by a growing caseload. In the early 1990s, a deal was struck to outsource most of its responsibilities to a new, more advanced crime lab in Chicago operated by the Illinois State Police Division of Forensic Services.

Mike Sheppo, the retired commander of the state police forensic services division, recalled that an expert evaluation of the Chicago police lab prior to the takeover found “a lot of concerns.”

By 1996, the new state lab assumed most of the caseload from Chicago. Under the deal, however, the Chicago lab retained responsibility for analyzing fingerprints lifted by police evidence technicians. Today, the Chicago police latent print unit works on fingerprints from property crime cases and any other cases “they deem necessary for their department,” according to a statement from the Illinois State Police.

City records show the Chicago police department currently is staffed by nine latent print examiners. The department did not respond to BGA questions about the fingerprint unit. Daniels did not return a phone message seeking comment. The Cook County State’s Attorney’s office, which uses fingerprint evidence from the Chicago police in the prosecution of crimes, also declined comment, citing pending litigation.

Brendan Max, chief of the public defender’s forensic science division, said fingerprints are sometimes the only evidence prosecutors have when bringing cases against suspects in burglaries and other property crimes.

“There are a surprising amount of cases in Chicago where guilt or innocence hinges directly on the testimony of a fingerprint examiner,” Max said. “There are jurisdictions around the country where that little amount of evidence will not suffice. But in Chicago, those can move forward.”

Max said he began raising concerns about the quality of fingerprint analysis by Chicago police after pre-trial interviews for a 2015 case revealed that an examiner lacked basic knowledge about his discipline. Along with colleagues at the public defender’s office, Max launched a deeper look into the department’s policies and practices by conducting interviews, examining casework, and subpoenaing the department for records from the fingerprint unit.

Forensic science expert Cedric Neumann, who reviewed the public defender’s research for that office, was even more critical.

“It is impossible that these collection of documents could guarantee any form of scientific rigor in the examinations performed by the latent print examiners,” wrote Neumann, who is on the faculty of South Dakota State University, in a report on his findings.

More broadly, the public defender’s office has said in court filings that its review of the unit revealed it does not have any written training materials. It also showed that the unit does not have a quality assurance program or error management system, something the FBI says is critical for any forensic lab.

Even so, Chicago fingerprint examiners often testify in court that they are “100 percent” certain in their conclusions, a practice discouraged as misleading by professional associations. “That is what I would consider old school and inappropriate testimony,” says Heidi Eldridge, a research forensic scientist and former latent print expert at a North Carolina-based non-profit research institute, in an interview with the BGA.

Some Chicago print examiners have testified in criminal cases they were unaware that asserting 100 percent certainty was no longer acceptable in the forensic science community, according to motions filed by the public defender’s office. CPD examiners have also testified they do not use blind analysis to compare fingerprints, a technique also urged by experts.

Blind analysis, which cuts down on the tendency to believe information that confirms pre-existing expectations, typically involves having an examiner scrutinize an unknown print before scrutinizing that of a suspect. That way they aren’t biased by the print they are seeking to match.

They also don’t provide good documentation of the reasons behind their decisions, said Langenburg. Examiners should keep detailed notes on the points on a print that they looked at to make a match and on the logic behind their choices, so that another examiner could easily look back and see how they came to their conclusion, he said. Langenburg said he reviewed a number of case files. “In some cases I viewed, we saw documentation that made zero sense to me,” he said. “It was really concerning in some cases.”

Hindering justice

The public defender’s office has increasingly invoked such problems to challenge the reliability of the evidence presented by the Chicago unit. The legal standards for forensic evidence to be admitted in court hinge on the idea that the evidence is reliable, said Langenburg: If labs don’t have standard operating procedures, they’re not documenting things properly and they’re not going through regular case reviews, their evidence doesn’t meet that standard.

In a recent bench trial for a residential burglary, for example, Judge Cynthia Ramirez found that a fingerprint lifted from a coin container at the scene and matched to a juvenile suspect was not enough to prove guilt beyond a reasonable doubt after hearing about problems with the fingerprint unit. In her decision, Ramirez both questioned the qualifications of the fingerprint examiner who made the match as well as the professionalism of the fingerprint unit as a whole.

“I’m also concerned about the fact that the CPD lab has no accreditation, no auditing system, no quality review, no error check process, no written professional development benchmarks, that there’s no standard operating procedures or guideline,” Ramirez said in her ruling.

The public defender’s office also has used challenges to the CPD’s fingerprint testimony to secure favorable plea deals for clients in about 10 cases, Max said. In those cases, the public defender’s office filed motions before the trials to exclude fingerprint evidence from CPD examiners. “The prosecutor, rather than respond, will just reduce the case and offer clients a deal they can’t refuse. We know the plea offers are a direct result of the prosecutor not wanting to confront the fingerprint challenges,” he said.

The same issues exist for all fingerprint evidence analyzed by the CPD. However, the public defender’s office can only point out those problems in cases without any other evidence. If, along with a print, the police collect DNA evidence, for example, it’s not credible to go in front of a jury and argue that the problems with the fingerprint lab matter. “We know we have a bad lab that shouldn’t be doing this work,” Max said. “In those cases, they get a pass because as a matter of strategy we can’t challenge them.”

That’s why specific challenges in court have only been made a handful of times since 2015, even though Max estimates that the public defender’s office sees hundreds of cases that include fingerprint evidence analyzed by the CPD each year. Daniels, who is no longer a member of the fingerprint unit (though he remains on the police force, the CPD confirmed), has said during testimony that he examined thousands of prints and made hundreds of matches in his career as a fingerprint examiner. He said he’s testified in court on more than ten occasions.

Max said problems with the fingerprint unit may help the public defender prevail in more cases, but added that the downside of that is that victims are less likely to receive justice. “There is a higher risk of innocent people being caught, and there is also a risk of suspects who are guilty of burglary not being discovered,” he said.

The problems in Chicago aren’t unique. The 2009 National Academy of Sciences report spurred a toughening of standards at many forensics labs, but responses to calls for reform have been uneven. Eldridge said there has been foot-dragging in many labs embedded in urban police departments.

“The more traditional, more police-based laboratories tend to be more resistant to change,” Eldridge said. “[Examiners] say, ‘Why are you making me do all this extra paperwork? I’ve been doing this for 30 years, I’ve been doing a good job.’”

Langenburg said police labs often only embrace change in response to scandal. “Suddenly, they fire all the people working at that agency, hire new people and consultants and turn the lab around,” Langenburg said.

He pointed to the St. Paul Police Department crime lab, which was found to use poor practices for drug testing in 2012, but then turned things around and achieved accreditation only after the issues were revealed.

It’s only a matter of time, he said, before each of the police department labs operating with poor standards and practices run into problems. “These large cities are just little time bombs waiting to go off.”